Interact with the bunny > (h act animation starts) > wait about 4 seconds, then press and hold the 0 key (zero key on QWERTY keyboards it is located above above P key and on the left side of Backspace) > hold that key until the white bar at the bottom of the screen fills up and the hact is canceled
The 0 icon can be seen at the bottom left corner of the screen. It is available in normal and tamed h acts, and usually not available on wild/forced h acts